Metallurgical product.



WALTER R'U'BEL, or BERLIN, GERMANY.

METALLURGICAL PRODUCT.

No Drawing.

To all whom it may concern:

Be it known that I, WALTER Rt'JBEL, a citizen of the Empire of Germany,residing at VVestend, Berlin, in the Empire of Germany, have invented anew and useful Metallurgical Product, of which the following isspecification.

As is well known, the iron used for electrical purposes, moreparticularly the iron sheets, requires to have certain properties whichcan be united only with great difliculty, in order to increase as far aspossible to a maximum the capacity and the useful effect of dynamos andelectromotors. The magnetizability should be as high as pos sible andthe losses of effect during the periodical magnetization should be aslow as possible, consequently the hysteresis and the electricalconductivity of the iron should be slight so as to keep as low aspossible the losses through the reversal of magnetism and through eddycurrents. The alloys of iron hitherto used for the known practicalpurposes permit only a comparatively small number of alternations, whichnumber lies between 50 and 100 per second. If with the material atpresent at disposal for dynamo sheets the number of 100 alternations persecond were to be exceeded, too great losses of energy would be producedby the heating of the iron cores. Also the cooling of the iron coreswould create too great difliculties. Endeavors have therefore been madefor a long time to produce for the construction of dynamos andelectromotors an iron material permitting alternation as rapid aspossible without creating the above mentioned dfsadvantages. Theessential point for these endeavors is, that the iron render possible aninlet and outlet as rapid possible of the magnetism without heating.

My detailed ex eriments have shown, that the usefulness o the varioussorts of iron for the purpose in consideration is very strongly reducedby an admixture of phosphorous, silicon and manganese, while slightcontaminations through sulfur and carbon are not so injurious.Furthermore the presence of other metals, such as for examplemolybdenum, titanium, cobalt, nickel and chrome, is objectionable. Inspite of all this the dynamo sheets at present in use contain slightquantities of manganese and silicon and phosphorus, because theinjuriousness of these admixtures has hitherto Specification of LettersPatent.

Patented July 23, 1912.

Application filed August 3, 1911. Serial No. 642,050.

not been sufiiciently recognized. For obtaining satisfactory dynamosheets it is necessary, as already mentioned, to remove as completely aspossible these contaminations, and this isthe purpose of my invention. Ihave furthermore discovered, that dynamo sheets made from iron which hasbeen perfectly freed from the contaminations recog nized as injurious,can be still rendered considerably more useful by the admixture of acertain percentage of copper. Practical tests have shown, that one percent. of copper will yield a very good effect. For certain purposes theadmixture of copper may be increased up to three per cent.

For the manufacture of the new material ordinary pig-iron is used, thatis a material containing phosphorus. The pig-iron is first nearlycompletely freed from phosphorus by the Thomas process. The iron freefrom phosphorus so obtained is then treated according to the Bessemerprocess in order to separate the silicon and the carbon. Thepurification of the iron can be driven so far that the iron isabsolutely free from silicon. Of course every addition of spiegeleisen,which is usual in the ordinary Bessemer process for adjusting thepercentage of carbon, must be entirely avoided, so as to obtain ironfree from manganese. To the iron as pure as possible so obtained isthenadded the required quantity of copper, which owing to its great specificweight sinks in the molten iron and dissolves therein. the blast shouldbe continued only for five minutes at the most, so as to avoid allunnecessary oxidation of the copper. A part of the copper, however, doesreact upon the oxygen still contained in the bath, but the copper 'oxidformed in this manner will by reason of its low specific weight rise tothe level of the molten alloy and can be easily removed before casting.After casting the bars are rolled into sheets, which by working areturned into dynamo sheets.

It is not absolutely necessary to produce the pure iron just in theorder above described. The pig-iron may also be first treated in theBessemer converter and then undergo the Thomas process, or it may betreated in electrical or Siemens furnaces suitable for carrying intoeifect both the acid and the basic processes. The essential point is,that an iron technically free from phosphorus, silicon and manganese beob- After the introduction of the copper tained. The purer the iron is,the better will be the success attained.

Although in general the percentage of copper is obtained by the additionof a cor responding quantity of metallic copper, yet in some cases theemployment of ores containing copper may be found useful for theprocess. Instead of the copper also other metals, such as for examplelead, silver and I0 bismuth or aluminium, may be used.

I claim: 1. A metallurgical product adapted for electrical purposeswhich comprises iron substantially free from phosphorus, silicon andmanganese, and containing copper.

2. metallurgical product adapted for electrical purposes which comprisesiron substantially free from phosphorus, silicon and manganese incombination with up to three per cent. of copper.

WALTER RUBEL.

Witnesses:

FRITZ WALTER, HENRY HASPER.

